Integrated circuit and an operation method thereof

ABSTRACT

An integrated circuit includes a control circuit, a first voltage generation circuit, and a second voltage generation circuit. The control circuit is coupled between a first voltage terminal and a first node, and generates an initiation voltage at the first node. The first voltage generation circuit and the second voltage generation circuit are coupled to a first capacitive unit at the first node and coupled to a second capacitive unit at a second node. The first voltage generation circuit generates, in response to the initiation voltage at the first node, a first control signal based on a first supply voltage to the second voltage generation circuit. The second voltage generation circuit generates, in response to the first control signal received from the first voltage generation circuit, a second control signal to the first node, based on a second supply voltage.

CROSS REFERENCE

The present application claims priority to China Application SerialNumber 202011238431.3 filed on Nov. 9, 2020, which is hereinincorporated by reference in its entirety.

BACKGROUND

De-coupling capacitance circuit is configured as an essential componentfor stabilization of power supply voltages in standard cell circuits ofintegrated circuit operating in high speed. Nonetheless, as thethickness of gate oxide layers in transistors of the integrated circuitsdevelops to get thinner, the de-coupling capacitance circuit is exposedin higher risk of electrostatic discharge.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A is a schematic diagram of part of an integrated circuit, inaccordance with some embodiments.

FIG. 1B is a schematic diagram of part of an integrated circuit, inaccordance with various embodiments.

FIG. 2 is detailed schematic diagram corresponding to the integratedcircuit in FIG. 1A, in accordance with some embodiments.

FIG. 3 is a layout diagram corresponding to the integrated circuit inFIG. 1A, in accordance with some embodiments.

FIG. 4 is detailed schematic diagram of an integrated circuitcorresponding to the integrated circuit in FIG. 1A, in accordance withvarious embodiments.

FIG. 5A is a layout diagram corresponding to the integrated circuit inFIG. 4 , in accordance with some embodiments.

FIG. 5B is a layout diagram corresponding to the integrated circuit inFIG. 4 , in accordance with various embodiments.

FIG. 6 is detailed schematic diagram of an integrated circuit of anintegrated circuit corresponding to the integrated circuit in FIG. 1A,in accordance with various embodiments.

FIG. 7 is detailed schematic diagram of an integrated circuitcorresponding to the integrated circuit in FIG. 1B, in accordance withvarious embodiments.

FIG. 8 is a layout diagram corresponding to the integrated circuit inFIG. 7 , in accordance with some embodiments.

FIG. 9 is detailed schematic diagram of an integrated circuitcorresponding to the integrated circuit in FIG. 1B, in accordance withvarious embodiments.

FIG. 10A is a layout diagram corresponding to the integrated circuit inFIG. 9 , in accordance with some embodiments.

FIG. 10B is a layout diagram corresponding to the integrated circuit inFIG. 9 , in accordance with various embodiments.

FIG. 11 is a flow chart of a method of operating an integrated circuit,in accordance with some embodiments.

FIG. 12 is a block diagram of a system for designing the integratedcircuit layout design, in accordance with some embodiments of thepresent disclosure.

FIG. 13 is a block diagram of an integrated circuit manufacturingsystem, and an integrated circuit manufacturing flow associatedtherewith, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

The terms used in this specification generally have their ordinarymeanings in the art and in the specific context where each term is used.The use of examples in this specification, including examples of anyterms discussed herein, is illustrative only, and in no way limits thescope and meaning of the disclosure or of any exemplified term.Likewise, the present disclosure is not limited to various embodimentsgiven in this specification.

As used herein, the terms “comprising,” “including,” “having,”“containing,” “involving,” and the like are to be understood to beopen-ended, i.e., to mean including but not limited to.

Reference throughout the specification to “one embodiment,” “anembodiment,” or “some embodiments” means that a particular feature,structure, implementation, or characteristic described in connectionwith the embodiment(s) is included in at least one embodiment of thepresent disclosure. Thus, uses of the phrases “in one embodiment” or “inan embodiment” or “in some embodiments” in various places throughout thespecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, implementation, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

As used herein, “around”, “about”, “approximately” or “substantially”shall generally refer to any approximate value of a given value orrange, in which it is varied depending on various arts in which itpertains, and the scope of which should be accorded with the broadestinterpretation understood by the person skilled in the art to which itpertains, so as to encompass all such modifications and similarstructures. In some embodiments, it shall generally mean within 20percent, preferably within 10 percent, and more preferably within 5percent of a given value or range. Numerical quantities given herein areapproximate, meaning that the term “around”, “about”, “approximately” or“substantially” can be inferred if not expressly stated, or meaningother approximate values.

Reference is now made to FIG. 1A. FIG. 1A is a schematic diagram of partof an integrated circuit 10, in accordance with some embodiments. Forillustration, the integrated circuit 10 includes a start-up circuit 100,a capacitive unit 200, and a capacitive unit 300. As shown in FIG. 1A,the start-up circuit 100 is coupled between the capacitive unit 200 andthe capacitive unit 300. The capacitive unit 200 and the capacitive unit300 are coupled to the supply voltage terminal VSS and the supplyvoltage terminal VDD respectively. In some embodiments, the supplyvoltage terminal VSS provides the supply voltage VSS (i.e., beingreferred to as a ground providing ground voltage,) and the supplyvoltage terminal VDD provides the supply voltage VDD. In someembodiments, the supply voltage VDD has a voltage level greater than thesupply voltage VSS.

As shown in FIG. 1A, the start-up circuit 100 includes a voltagegeneration circuit 110, a voltage generation circuit 120, and a controlcircuit 130. The voltage generation circuit 110 and the voltagegeneration circuit 120 are coupled to the capacitive unit 200 at thenode N1. The voltage generation circuit 110 and the voltage generationcircuit 120 are coupled to the capacitive unit 300 at the node N2. Thecontrol circuit 130 is coupled between the capacitive unit 200 and thenode N1. In some embodiments, the voltage generation circuit 110 iscoupled to the supply voltage terminal VDD. The voltage generationcircuit 120 and the control circuit 130 are coupled to the supplyvoltage terminal VSS. Alternatively stated, the control circuit 130 iscoupled between the supply voltage terminal VSS and the voltagegeneration circuit 120.

In some embodiments, integrated circuit 10 is configured to operate as ade-couping circuit. Specifically, in some embodiments, the controlcircuit 130 is configured to generate an initiation voltage at the nodeN1. The voltage generation circuit 110 transmits, in response to theinitiation voltage at the node N1, the supply voltage VDD from thesupply voltage terminal VDD to the voltage generation circuit 120.Consequently, the voltage generation circuit 120 transmits, in responseto the supply voltage VDD from the voltage generation circuit 110, thesupply voltage VSS different from the supply voltage VDD to the node N1.Alternatively stated, the voltage level of the node N1 is pulled downfrom the initiation voltage to the supply voltage VSS by the voltagegeneration circuit 120. In some embodiments, the voltage generationcircuit 120 is a pull down circuit.

In addition, as shown in FIG. 1A, the start-up circuit 100 is configuredto output the voltage level of the node N1 as the control signal CS1 tothe capacitive unit 200, and to output the voltage level of the node N2as the control signal CS2 to the capacitive unit 300. The capacitiveunit 200 and the capacitive unit 300 receive the control signal CS1 andCS2 from the start-up circuit 100 to operate separately. as mentionedabove, when the voltage generation circuit 110 pulls up the voltagelevel of the node N2 to the supply voltage VDD and the voltagegeneration circuit 120 pulls down the voltage level of the node N1 tothe supply voltage VSS, there is significant voltage difference betweentwo terminals of each of the capacitive unit 200 and the capacitive unit300. Accordingly, the capacitive unit 200 and the capacitive unit 300have high capacitance values. The details of operations of theintegrated circuit 10 will be discussed in the following paragraphs.

As mentioned above, in some embodiments, the voltage generation circuit110 is further configured to generate based on the supply voltage VDD,in response to the initiation voltage generated by the control circuit130, the control signal CS2 to the voltage generation circuit 120. Thevoltage generation circuit 120 is configured to generate based on thesupply voltage VSS, in response to the control signal CS2 received fromthe voltage generation circuit 110, the control signal CS1 to the nodeN1.

Reference is now made to FIG. 1B. FIG. 1B is a schematic diagram of partof the integrated circuit 10, in accordance with various embodiments.With respect to the embodiments of FIG. 1A, like elements in FIG. 1B aredesignated with the same reference numbers for ease of understanding.The specific operations of similar elements, which are already discussedin detail in above paragraphs, are omitted herein for the sake ofbrevity.

Compared with FIG. 1A, instead of the control circuit 130 being coupledbetween the node N1 and the capacitive unit 200, the control circuit 130in FIG. 1B is coupled between the node N2 and the capacitive unit 300.In some embodiments, the control circuit 130 is configured to generatethe initiation voltage at the node N2. The voltage generation circuit120 transmits, in response to the initiation voltage at the node N2, thesupply voltage VSS from the supply voltage terminal VSS to the voltagegeneration circuit 110. Consequently, the voltage generation circuit 110transmits, in response to the supply voltage VSS from the voltagegeneration circuit 120, the supply voltage VSS different from the supplyvoltage VDD to the node N2. Alternatively stated, the voltage level ofthe node N2 is pulled up from the initiation voltage to the supplyvoltage VDD by the voltage generation circuit 110. In some embodiments,the voltage generation circuit 110 is a pull up circuit.

Reference is now made to FIG. 2 . FIG. 2 is detailed schematic diagramcorresponding to the integrated circuit 10 in FIG. 1A, in accordancewith some embodiments. As shown in FIG. 2 , the voltage generationcircuit 110 in the start-up circuit 100 includes a P-type transistor M0.The voltage generation circuit 120 includes an N-type transistor M1. Thecontrol circuit 130 includes an N-type transistor M2. In someembodiments, the transistors M0-M2 are implemented bymetal-oxide-semiconductor field-effect transistors (MOSFET). A gate ofthe transistor M0 is coupled to the node N1, a source of the transistorM0 is coupled to the supply voltage VDD, and the source of thetransistor M0 is coupled to the node N2. A gate of the transistor M1 iscoupled to the node N2, a source of the transistor M1 is coupled to thesupply voltage VSS, and a drain of the transistor M1 is coupled to thenode N1. A gate and a source of the transistor M2 are coupled to thenode N1, and a source of the transistor M2 is coupled to the supplyvoltage VSS.

The capacitive unit 200 includes a P-type transistor M3 and thecapacitive unit 300 includes an N-type transistor M4. A gate of thetransistor M3 is coupled the transistors M0-M2 at the node N1, and asource and a drain of the transistor M3 and the supply voltage terminalVDD are coupled with each other. A gate of the transistor M4 and thetransistor M0-M2 are coupled at the node N2, and a source and a drain ofthe transistor M4 and the supply voltage terminal VSS are coupled witheach other.

In some embodiments, in operation, the transistor M2 operates as adiode. Specifically, in an initial stage, the transistor M2 generates atthe node N1 the initiation voltage equal a threshold voltage of thetransistor M2. The initiation voltage is a low voltage level withrespect to the supply voltage VDD. Accordingly, the control signal CS1having the voltage level of the node N1 is referred to as having a logicvalue 0. Consequently, the transistor M0 is turned on in response to thecontrol signal CS1 which has the logic value 0 (i.e., the voltage levelof the node N1) and is received at the gate of the transistor M0, andthe voltage level of the node N2 is adjusted based on the supply voltageVDD. Correspondingly, the voltage level of the node N2 is the supplyvoltage VDD, the control signal CS2 having the voltage level of the nodeN2 is referred to as having a logic value 1. The transistor M1 is turnedon in response to the control signal CS2 which has the logic value 1(i.e., the voltage level of the node N2) and is received at the gate ofthe transistor M1, and the voltage level of the node N1 is adjustedbased on the supply voltage VSS. Accordingly, the voltage level of thenode N1 is pulled down from the initiation voltage, equal the thresholdvoltage of the transistor M2, to the supply voltage VSS. In someembodiments, the supply voltage terminal VSS is a ground terminal, andthe voltage level of the node N1 is the voltage level of the ground.

Based on the discussions above, when the control signal CS1 has thelogic value 0, the transistor M3 is turned on. When the control signalCS2 has the logic value 1, the transistor M4 is turned on. In themeanwhile, because the voltage generation circuit 110 and the voltagegeneration circuit 120 provide stable voltages to the nodes N1 and N2,the transistor M3 and the transistor M4 have steady gate clamp voltages,occupy meager areas and being de-coupling capacitors with greatcapacitance.

As shown in FIG. 2 , in some embodiments, the integrated circuit 10 isin an ESD positive-to-VSS mode (i.e., ESD PS mode), and an ESD currentbetween the supply voltage terminal VDD and the supply voltage terminalVSS is discharged by three electrostatic discharge paths P1-P3.

Specifically, the control circuit 130 including the transistor M2 andthe capacitive unit 200 including the transistor M3 are configured asthe electrostatic discharge path P1. A first portion of the ESD currentbetween the supply voltage terminal VDD and the supply voltage terminalVSS flows out from the drain and the source of the capacitive unit 200through the gate (i.e., being referred to as the gate oxide layer)thereof, the node N1, the drain and the source of the transistor M2 tothe supply voltage terminal VSS.

In addition, the voltage generation circuit 120 including the transistorM1 and the capacitive unit 200 including the transistor M3 areconfigured as the electrostatic discharge path P2. A second portion ofthe ESD current between the supply voltage terminal VDD and the supplyvoltage terminal VSS flows out from the drain and the source of thecapacitive unit 200 to the supply voltage terminal VSS through the gate(i.e., being referred to as the gate oxide layer) thereof, the node N1,the drain and the source of the transistor M1.

Moreover, the voltage generation circuit 110 including the transistor M0and the capacitive unit 300 including the transistor M4 are configuredas the electrostatic discharge path P3. A third portion of the ESDcurrent between the supply voltage terminal VDD and the supply voltageterminal VSS flows out from the drain and the source of the transistorM0, through the gate (i.e., being referred to as the gate oxide layer)of the capacitive unit 300 and the drain and the source of thecapacitive unit 300 to the supply voltage terminal VSS.

In some approaches, gates of elements, similar to the capacitive units200 and 300, in a de-coupling circuit are coupled directly. When a gateoxide layer has a tendency to get thinner and thinner, a breakdownvoltage of a transistor consisting of a capacitive unit declines.Therefore, in those approaches, the de-coupling circuit tends to bestruck vulnerably by the ESD current and/or be broken down. On thecontrary, with the configurations of FIGS. 1A-2 , the gates of thecapacitive units 200 and 300 are firstly coupled to the start-up circuit100 which includes the nodes N1 and N2 of an inner network. Accordingly,it avoid the gate oxide layer from being broken down. In the meanwhile,with the electrostatic discharge paths consisted of the voltagegeneration circuits 110-120 and the control circuit 130, the ability ofthe integrated circuit for ESD protection is enhanced. In someembodiments of the present disclosure, the breakdown voltage as a wholesurges around 30% to around 50%.

In further comparison, in some approaches, gate voltages of theelements, similar to the capacitive units 200 and 300 are undetermined,and are charged slowly by leakage currents in a relevant network. Insuch arrangements, it takes a period of time to initiate the circuit.Compared with the present disclosure, by the determined initiationvoltage (i.e., a threshold voltage) provided by the control circuit 130,the voltage generation circuits 110-120 respond rapidly and generatevoltages (having certain logic states) at the nodes N1-N2. Accordingly,compared with some approaches, the circuit, in one of the embodiments ofthe present disclosure act quicker than one in some approaches, and noextra charging time is required. The start speed of the integratedcircuit in one of the embodiments of the present disclosure is around20% faster than that of some approaches.

In addition, in some other approaches, the circuit can only utilizeP-type transistors as capacitive units, and extra circuit is needed forusing N-type transistors as capacitive units. At the same time, the gatevoltages of the elements, similar to the capacitive units 200 and 300are undetermined, and accordingly, significant area is required forincreasing the capacitance values of the capacitive units in someapproaches. Therefore, the integrated circuit suffers from the areapenalty. However, the configurations of the present disclosure includeP-type transistors and N-type transistors for capacitive units, andsteady gate voltages are provided for the capacitive units. Comparedwith some approaches, the present disclosure provides greatercapacitance values in a smaller area.

The configurations of FIGS. 1A-2 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, the integrated circuit 10is in an ESD negative-to-VDD mode (ESD ND mode), the ESD current betweenthe supply voltage terminal VDD and the supply voltage terminal VSS isalso discharge in the aforementioned electrostatic discharge path P1-P3.The flowing direction of the ESD current in the ESD ND mode is contraryto that in the PS mode, while other configurations are similar.Accordingly, the repetitious descriptions are omitted herein.

Reference is now made to FIG. 3 . FIG. 3 is a layout diagramcorresponding to the integrated circuit 10 in FIG. 1A, in accordancewith some embodiments. With respect to the embodiments of FIGS. 1A-2 ,like elements in FIG. 3 are designated with the same reference numbersfor ease of understanding.

As shown in FIG. 3 , the integrated circuit 10 includes active regions(i.e., oxide device) 301-307, gates (i.e., Poly) 401-409, conductivesegments (i.e., metal on diffusion, MD) 501-507, conductive lines (i.e.,metal zero layer, M0) 601-604 and vias VD1-VD14, VG1-VG5. In someembodiments, the active region 301-307 are arranged in a first layer,the gates 401-409 and the conductive segments 501-507 are arranged in asecond layer above the first layer. The conductive lines 601-604 arearranged in a third layer above the second layer. The vias VD1-VD14 arearranged between the first layer and the second layer or between thesecond layer and the third layer. The vias VG1-VG5 are arranged betweenthe second layer and the third layer.

In some embodiments, the gate 402 corresponds to the gate of thetransistor M3, the conductive segment 501 corresponds to thedrain/source of the transistor M3, and the conductive segment 502corresponds to the source/drain of the transistor M3 and the source ofthe transistor M0. The gate 403 corresponds to the gate of thetransistor M0, the conductive segment 503 corresponds to the drain ofthe transistor M0. The gate 406 corresponds to the gate of thetransistor M4, the conductive segment 504 corresponds to thedrain/source of the transistor M4, and the conductive segment 505corresponds to the source/drain of the transistor M4 and the source ofthe transistor M1. The gate 407 corresponds to the gate of thetransistor M1, the conductive segment 506 corresponds to the drain ofthe transistor M1 and the drain of the transistor M2. The gate 408corresponds to the gate of the transistor M2, the conductive segment 507corresponds to the source of the transistor M2. In some embodiments, thegates 401, 404, 405, and 409 are configured as dummy gates, in which insome embodiments, “dummy gate” are referred to as being not electricallyconnected as the gate for MOS devices, having no function in thecircuit.

For illustration, as shown in FIG. 3 , the active regions 301-307 extendin x direction. In some embodiments, the active regions 301-303 areincluded in an active area arranged in an N-type well (NW), in which theN-type is arranged on a substrate (not shown). The active regions304-307 are arranged on the substrate or in another active area arrangedin a P-type well.

The gates 401-409 extend in y direction. The gates 401-404 are separatedfrom each other in x direction, and the gates 405-409 are separated fromeach other in x direction. As shown in FIG. 3 , the gate 402 is arrangedbetween the active regions 301 and 302. The gate 403 is arranged betweenthe active region 302 and 303. The gate 406 is arranged between theactive region 304 and 305. The gate 407 is arranged between the activeregion 305 and 306. The gate 408 is arranged between the active region306 and 307. In some embodiments, the gates 401-404 in a layout diagramcrosses over the active area including the active regions 301-303, andthe gates 405-409 in the layout diagram crosses the active areaincluding the active regions 304-307.

The conductive segments 501-507 extend in y direction. For illustration,the conductive segment 501 crosses the active region 301, the conductivesegment 502 crosses the active region 302, the conductive segment 503crosses the active region 303, the conductive segment 504 crosses theactive region 304, the conductive segment 505 crosses the active region305, the conductive segment 506 crosses the active region 306 and theconductive segment 507 crosses the active region 307.

The conductive lines 601-604 extend in x direction, and are separatedfrom each other in y direction. In some embodiments, the conductivelines 601 and 602 are configured to transmit the supply voltages VDD andVSS, respectively, to the integrated circuit 10. The conductive line 603corresponds to the node N1. The conductive line 604 corresponds to thenode N2.

Regarding the connection relationship, the active region 301 is coupledto the conductive segment 501 by the via VD5, and the conductive segment501 is coupled to the conductive line 601 through the via VD6 to receivethe supply voltage VDD. Similarly, the active region 302 is coupled tothe conductive segment 502 through the via VD3, and the conductivesegment 502 is coupled to the conductive line 601 through the via VD4 toreceive the supply voltage VDD. The gate 402 is coupled to theconductive line 603 through the via VG2. As mentioned above, the drainand the source of the transistor M3 and the drain of the transistor M0are coupled to the supply voltage terminal VDD, and the gate of thetransistor M3 is coupled to the node N1.

The gate 403 is coupled to the conductive line 603 through the via VG1.The active region 303 is coupled to the conductive segment 503 throughthe via VD1, and the conductive segment 503 is coupled to the conductiveline 604 through the via VD2. As mentioned above, the drain of thetransistor M0 is coupled to the node N2 and the gate of the transistorM0 is coupled to the node N1.

The active region 304 is coupled to the conductive segment 504 throughthe via VD13, and the conductive segment 504 is coupled to theconductive line 602 through the via VD14 to receive the supply voltageVSS. Similarly, the active region 305 is coupled to the conductivesegment 505 through the via VD11, and the conductive segment 505 iscoupled to the conductive line 602 through the via VD12 to receive thesupply voltage VSS. The gate 406 is coupled to the conductive line 604through the via VG5. As mentioned above, the drain and the source of thetransistor M4 and the source of the transistor M1 are coupled to thesupply voltage terminal VSS, and the gate of the transistor M4 iscoupled to the node N2.

The gate 407 is coupled to the conductive line 604 through the via VG4.The active region 306 is coupled to the conductive segment 506 throughthe via VD8, and the conductive segment 506 is coupled to the conductiveline 603 through the via VD7. As mentioned above, the source of thetransistor M1 is coupled to the node N1 and the gate of the transistorM1 is coupled to the node N2.

The gate 408 is coupled to the conductive line 603 through the via VG3.The active region 307 is coupled to the conductive segment 507 throughthe via VD9, and the conductive segment 507 is coupled to the conductiveline 602 through the via VD10. As mentioned above, the gate of thetransistor M2 is coupled to the node N1 and the gate of the transistorM2 is coupled to the supply voltage terminal VSS.

In some embodiments, a portion of the ESD current between the supplyvoltage terminal VDD and the supply voltage terminal VSS is dischargedby the semiconductor structure of the transistors M1-M3 and theconductive line 603. In some alternative embodiments, another portion ofthe ESD current is discharged by the transistors M0, M4 and theconductive line 604.

The configurations of FIG. 3 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, according to the actualrequirement of ESD protection, at least two of the transistors M0-M4 donot share active regions.

Reference is now made to FIG. 4 . FIG. 4 is detailed schematic diagramof an integrated circuit 20 corresponding to the integrated circuit 10in FIG. 1A, in accordance with various embodiments. In some embodiments,the integrated circuit 20 is configured with respect to, for example,the integrated circuit 10. With respect to the embodiments of FIGS. 1A-3, like elements in FIG. 4 are designated with the same reference numbersfor ease of understanding.

Compared with FIG. 2 , each of the voltage generation circuit 110, thevoltage generation circuit 120 and the control circuit 130 in theintegrated circuit 20 further includes multiple transistors coupled inseries. Specifically, the voltage generation circuit 110 furtherincludes a P-type transistor M5 coupled in series with the transistorM0. The voltage generation circuit 120 further includes an N-typetransistor M5 coupled in series with the transistor M1. The controlcircuit 130 further includes an N-type transistor M6 coupled in serieswith the transistor M2.

As shown in FIG. 4 , a gate of the transistor M5 and a gate of thetransistor M0 coupled at the node N1. Compared with FIG. 2 , instead ofthe source of the transistor M0 being directly coupled to the supplyvoltage terminal VDD, in FIG. 4 the source of the transistor M0 iscoupled to and the drain of the transistor M5, and the source of thetransistor M5 is coupled to the supply voltage terminal VDD. Similarly,the gate of the transistor M6 and the gate of the transistor M1 arecoupled at the node N2. Compared with FIG. 2 , instead of the source ofthe transistor M1 being directly coupled to the supply voltage terminalVSS, in FIG. 4 the source of the transistor M1 is coupled to the drainof the transistor M6, and the source of the transistor M6 is coupled tothe supply voltage terminal VSS. In addition, the gate of the transistorM7 and the gate of the transistor M2 are coupled at the node N1.Compared with FIG. 2 , instead of the source of the transistor M2 beingdirectly coupled to the supply voltage terminal VSS, in FIG. 4 thesource of the transistor M2 is coupled to the drain of the transistorM7, and the source of the transistor M7 is coupled to the supply voltageterminal VSS.

In some embodiments, the voltage generation circuit 110, the voltagegeneration circuit 120, and the control circuit 130 form as amultiple-stage circuit by including multiple transistors in order tomeet the requirements of ESD protection capacity while operating theintegrated circuit 20. In various embodiments, with the configurationsof each one of the voltage generation circuit 110 and the voltagegeneration circuit 120 including two stages transistor circuit shown inFIG. 4 , a break down voltage of the integrated circuit 20 increases 1.0Volts.

The configurations of FIG. 4 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, each of the voltagegeneration circuit 110, the voltage generation circuit 120 and thecontrol circuit 130 of the integrated circuit 20 includes more than twotransistors coupled in series with each other.

Reference is now made to FIG. 5A. FIG. 5A is a layout diagramcorresponding to the integrated circuit 20 in FIG. 4 , in accordancewith some embodiments. With respect to the embodiments of FIGS. 1A-4 ,like elements in FIG. 5A are designated with the same reference numbersfor ease of understanding.

Compared with FIG. 3 , the integrated circuit 20 further includes activeregions 308-311, gates 410-413, a conductive segment 510 and viasVD15-VD16. The active regions 308-311 are configured with respect to,for example, the active region 303. The gates 410-413 are configuredwith respect to, for example, the gate 403. In some embodiments, thegate 413 is configured as a dummy gate. The conductive segment 510 isconfigured with respect to, for example, the conductive segment 505. Thevias VD15-VD16 are configured with respect to, for example, the viaVD14.

In some embodiments, the active region 302 corresponds to the source ofthe transistor M5, the gate 410 corresponds to the gate of thetransistor M5, and the active region 308 corresponds to the drain of thetransistor M5 and the source of the transistor M0. The gate 410 iscoupled to the conductive line 603 through the via VG6. Accordingly, thegate of the transistor M5 is coupled to the node N1, the source of thetransistor M5 is coupled to the supply voltage terminal VDD, and thedrain of the transistor M5 is coupled to the gate of the transistor M0.

The active region 305 corresponds to the source of the transistor M6,the gate 411 corresponds to the source of the transistor M6, and theactive region 309 corresponds to the gate of the transistor M6 and thedrain of the transistor M1. The gate 411 is coupled to the conductiveline 604 through the via VG7. Accordingly, the gate of the transistor M6is coupled to the node N2, the source of the transistor M6 is coupled tothe supply voltage terminal VSS, and the drain of the transistor M6 iscoupled to the gate of the transistor M1.

The active region 311 corresponds to the source of the transistor M7,the gate 412 corresponds to the gate of the transistor M7, and theactive region 310 corresponds to the drain of the transistor M7 and thesource of the transistor M2. The gate 412 is coupled to the conductiveline 603 through the via VG8. The active region 311 is coupled to theconductive segment 510 through the via VD13, and the conductive segment510 is coupled to the conductive line 602 through the via VD16.Accordingly, the gate of the transistor M7 is coupled to the node N1,the source of the transistor M7 is coupled to the supply voltageterminal VSS, and the drain of the transistor M7 is coupled to thesource of the transistor M2.

Reference is now made to FIG. 5B. FIG. 5B is a layout diagramcorresponding to the integrated circuit 20 in FIG. 4 , in accordancewith various embodiments. With respect to the embodiments of FIGS.1A-5A, like elements in FIG. 5B are designated with the same referencenumbers for ease of understanding.

Compared with FIG. 5A, with regard to transistors sharing activeregions, part of the active regions of the transistors in FIG. 5B areseparated from each other. As shown in FIG. 5B, the integrated circuit20 further includes active regions 308 a-308 b, 309 a-309 b, 310 a-310b, gates 414-419, conductive segments 511-513 and vias VD17-22. In someembodiments, the active regions 308 a-308 b correspond to a firstportion and a second portion of the active region 308 in FIG. 5A. Theactive regions 309 a-309 b correspond to a first portion and a secondportion of the active region 309 in FIG. 5A. The active regions 310a-310 b correspond to a first portion and a second portion of the activeregion 310 in FIG. 5A. The gates 414-419 are configured with respect to,for example, the gate 413. In some embodiments, the gates 414-419 aredummy gates. The conductive segments 511-513 are configured with respectto, for example, the conductive segment 503. The vias VD17-VD22 areconfigured with respect to, for example, the via VD1.

In some embodiments, the gates 414-415 are not electrically connectedwith the conductive segment 511. The gates 416-417 are not electricallyconnected with the conductive segment 512. The gates 418-419 are notelectrically connected with the conductive segment 513.

In some embodiments, the active region 308 a corresponds to the drain ofthe transistor M5, and the active region 308 b corresponds to the sourceof the transistor M0. In addition, the active regions 308 a-308 b areseparated from each other in x direction. Alternatively stated, thetransistors M0 and M5 do not share the active region, are referred to ashaving structures of separated active regions (separate OD). In someembodiments, the ESD resistance performance of the integrated circuit 20is enhanced by around 20%. In various embodiments, the occupied area ofseparated active regions and the ESD resistance performance areconsidered comprehensively in designing the integrated circuit 20.

Similarly, the active region 309 a corresponds to the drain of thetransistor M6, and the active region 309 b corresponds to the source ofthe transistor M1. The active regions 309 a-309 b are separated fromeach other in x direction. Alternatively stated, the transistors M1 andM6 do not share the active region.

The active region 310 a corresponds to the drain of the transistor M7,and the active region 310 b corresponds to the source of the transistorM2. The active regions 310 a-310 b are separated from each other in xdirection. Alternatively stated, the transistors M2 and M7 do not sharethe active region.

The configurations of FIGS. 5A-5B are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, the structure design ofseparated active regions is adapted for all of active regions in theintegrated circuit 20.

Reference is now made to FIG. 6 . FIG. 6 is detailed schematic diagramof an integrated circuit 30 corresponding to the integrated circuit 10in FIG. 1A, in accordance with various embodiments. With respect to theembodiments of FIGS. 1A-5B, like elements in FIG. 6 are designated withthe same reference numbers for ease of understanding.

Compared with FIG. 4 , the integrated circuit 30 further includes aP-type transistor M8. A drain of the transistor M8 is coupled to thesource of the transistor M5, a source of the transistor M8 is coupled tothe supply voltage terminal VDD, and the gate of the transistor M8 iscoupled to the gates of the transistors M5 and M0 at the node N1.

In some embodiments, a number of P-type transistors in the voltagegeneration circuit 110 is different from a number of N-type transistorsin the voltage generation circuit 120 and a number of N-type transistorsin the control circuit 130. As shown in FIG. 6 , the voltage generationcircuit 110 includes three P-type transistors, and the voltagegeneration circuit 120 and the control circuit 130 includes two N-typetransistors respectively.

As mentioned above, the number of P-type transistors in the voltagegeneration circuit 110 is different from a sum of the number of N-typetransistors in the voltage generation circuit 120 and the number ofN-type transistors in the control circuit 130. As shown in theembodiments of FIG. 6 , the number of N-type transistors in the voltagegeneration circuit 120 and the control circuit 130 is greater than thenumber of P-type transistors in the voltage generation circuit 110. Insome embodiments, due to the manufacture process and physicalproperties, the N-type transistors' tolerance to ESD is lower than thatof the P-type transistors. Therefore, the start-up circuit 100 includesfewer P-type transistors and also meets the ESD performance requirementsof the integrated circuit 30.

The configurations of FIG. 6 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, the voltage generationcircuit 110 and the voltage generation circuit 120 of the integratedcircuit 30 include the same quantity of transistors, for example, threeN-type transistors.

Reference is now made to FIG. 7 . FIG. 7 is detailed schematic diagramof an integrated circuit 40 corresponding to the integrated circuit 10in FIG. 1B, in accordance with various embodiments. With respect to theembodiments of FIGS. 1A-6 , like elements in FIG. 7 are designated withthe same reference numbers for ease of understanding.

As shown in FIG. 7 , the control circuit 130 includes a P-typetransistor M9. A gate and a drain of the transistor M9 are coupled thenode N2. The source of the transistor M9 is coupled the supply voltageterminal VDD.

Compared with FIG. 2 , instead of the control circuit 130 beingconfigured to provide the initiation voltage at the node N1, in theembodiments of FIG. 7 , the control circuit 130 is configured to providethe initiation voltage at the node N2. In some embodiments, inoperation, the transistor M9 operates as a diode. Specifically, in theinitiation stage, the transistor M9 generates the initiation voltage atthe node N2, in which the initiation voltage is associated with athreshold voltage (i.e., Vth) of the transistor M9 and the supplyvoltage VDD, being the supply voltage VDD subtracts the thresholdvoltage of the transistor M9 (VDD-Vth). The initiation voltage is a highvoltage level with respect to the supply voltage VSS. Accordingly, thecontrol signal CS2 having the voltage level of the node N2 is referredto as having the logic value 1. Consequently, the transistor M1 isturned on in response to the control signal CS2 which has the logicvalue 1 (i.e., the voltage level of the node N2) and is received at thegate of the transistor M1, and the voltage level of the node N1 isadjusted based on the supply voltage VSS. Correspondingly, the voltagelevel of the node N1 is the supply voltage VSS, and the control signalCS1 having the voltage level of the node N1 is referred to as having thelogic value 0. The transistor M0 is turned on in response to the controlsignal CS1 which has the logic value 0 (i.e., the voltage level of thenode N1) and is received at the gate of the transistor M0, and thevoltage level of the node N2 is adjusted based on the supply voltageVDD. Accordingly, the voltage level of the node N2 is pulled up from theinitiation voltage, equal the voltage of VDD-Vth, to the supply voltageVDD. The configurations of the integrated circuit 40 of FIG. 7 aresimilar to the integrated circuit 10. Hence, the repetitiousdescriptions are omitted here.

In addition, the ESD current between the supply voltage terminal VDD andthe supply voltage terminal VSS is further discharged by theelectrostatic discharge path P4. Specifically, the control circuit 130including the transistor M9 and the capacitive unit 300 including thetransistor M4 are configured as the electrostatic discharge path P4.Part of the ESD current between the supply voltage terminal VDD and thesupply voltage terminal VSS flows out from the supply voltage terminalVDD to the gate (being referred as to the gate oxide layer) of thecapacitive unit 300 through the source and the drain of the transistorM9 and the node N2, and further flows to the supply voltage terminal VSSthrough the source and the drain of the capacitive unit 300.

The configurations of FIG. 7 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, the voltage generationcircuit 120 includes multiple N-type transistors, for example, more thantwo N-type transistors.

Reference is now made to FIG. 8 . FIG. 8 is a layout diagramcorresponding to the integrated circuit 40 in FIG. 7 , in accordancewith some embodiments. With respect to the embodiments of FIGS. 1A-7 ,like elements in FIG. 8 are designated with the same reference numbersfor ease of understanding.

Compared with FIG. 3 , instead of including relevant structurescorresponding to the transistor M2, the integrated circuit 40 includesan active region 312, a gate 420, a conductive segment 514 and the viasVD23-VD24. The active region 312 is configured with respect to, forexample, the active region 303. The gate 420 is configured with respectto, for example, the gate 413. In some embodiments, the gate 420 is adummy gate. The conductive segment 514 is configured with respect to,for example, the conductive segment 502. The vias VD23-VD24 areconfigured with respect to, for example, the via VD4.

In some embodiments, the active region 303 corresponds to the gate ofthe transistor M0 and the drain of the transistor M9, the gate 404corresponds to the gate of the transistor M9, and the active region 312corresponds to the source of the transistor M9. The gate 404 is coupledto the conductive line 604 through the via VG9. The active region 312 iscoupled to conductive segment 514 through the via VD23, and theconductive segment 514 is coupled to the conductive line 601 through thevia VD24. Accordingly, the gate and the drain of the transistor M9 arecoupled to the node N2, and the source of the transistor M9 is coupledto the supply voltage terminal VDD.

In some embodiments, a portion of the ESD current between the supplyvoltage terminal VDD and the supply voltage terminal VSS is dischargedby the semiconductor structure of the transistors M0, M4, M9 and theconductive line 604. In various embodiments, another portion of the ESDcurrent is discharged by the transistors M1, M3 and the conductive line603.

The configurations of FIG. 8 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, the integrated circuit 40in FIG. 8 includes structures of separated active regions.

Reference is now made to FIG. 9 . FIG. 9 is detailed schematic diagramof an integrated circuit corresponding to the integrated circuit in FIG.1B, in accordance with various embodiments. With respect to theembodiments of FIGS. 1A-8 , like elements in FIG. 9 are designated withthe same reference numbers for ease of understanding.

Compared with FIG. 4 , instead of the control circuit 130 includingmultiple N-type transistors, the control circuit 130 in FIG. 9 includesmultiple P-type transistors M9-M10 that are coupled in series. A gate ofthe transistor M10 and a gate of the transistor M9 are coupled at thenode N2, a source of the transistor M9 is coupled to a drain of thetransistor M10, and a source of the transistor M10 is coupled to thesupply voltage terminal VDD.

The configurations of FIG. 9 are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, a number of multipleN-type transistors included in the voltage generation circuit 120 isgreater than a sum of a number of P-type transistors included in thevoltage generation circuit 110 and a number of P-type transistorsincluded in the control circuit 130.

Reference is now made to FIG. 10A. FIG. 10A is a layout diagramcorresponding to the integrated circuit 50 in FIG. 9 , in accordancewith some embodiments. With respect to the embodiments of FIGS. 1-9 ,like elements in FIG. 10A are designated with the same reference numbersfor ease of understanding.

Compared with FIG. 5A, instead of including relevant structurescorresponding to the transistors M2 and M7, the integrated circuit 50includes an active region 313, gates 421-422, a conductive segment 515and vias VD25-VD26. The active region 313 is configured with respect to,for example, the active region 312. The gates 421-422 are configuredwith respect to, for example, the gate 404. In some embodiments, thegate 422 is a dummy gate. The conductive segment 515 is configured withrespect to, for example, the conductive segment 505. The vias VD25-VD26are configured with respect to, for example, the via VD4. The via VG9 isconfigured with respect to, for example, the via VG8.

In some embodiments, the active region 313 corresponds to a source ofthe transistor M10, the gate 421 corresponds to a gate of the transistorM10, and the active region 312 corresponds to a drain of the transistorM10 and a source of the transistor M9. The gate 421 is coupled to theconductive line 604 through the via VG10. Accordingly, the gate of thetransistor M10 is coupled to the node N2, the source of the transistorM10 is coupled to the supply voltage terminal VDD, and the drain of thetransistor M10 is coupled to the source of the transistor M9.

Reference is now made to FIG. 10B. FIG. 10B is a layout diagramcorresponding to the integrated circuit 50 in FIG. 9 , in accordancewith various embodiments. With respect to the embodiments of FIGS.1A-10A, like elements in FIG. 10B are designated with the same referencenumbers for ease of understanding.

Compared with FIG. 10A, with regard to transistors sharing activeregions, portions of the active areas included in the transistors inFIG. 10B are separated with each other. As shown in FIG. 10B, comparedwith FIG. 5B, the integrated circuit 50 further includes active regions312 a-312 b, gates 423-424, a conductive segment 516 and vias VD27-28.In some embodiments, the active regions 312 a-312 b correspond to afirst portion and a second portion of the active region 312 in FIG. 10A.The gates 423-424 are configured with respect to, for example, the gates414-415. In some embodiments, the gates 423-424 are dummy gates. Theconductive segment 516 is configured with respect to, for example, theconductive segment 512. The vias VD27-VD28 are configured with respectto, for example, the via VD17.

In some embodiments, the gates 423-424 are not electrically connectedwith the conductive segment 516.

In some embodiments, the active region 312 a corresponds to the sourceof the transistor M9, and the active region 312 b corresponds to thedrain of the transistor M10. In addition, the active regions 312 a-312 bare separated from each other in x direction. Alternatively stated, thetransistors M9 and M10 do not share active regions.

The configurations of FIGS. 10A-10B are given for illustrative purposes.Various implements are within the contemplated scope of the presentdisclosure. For example, in some embodiments, all of the active regionsin the integrated circuit 50 have separated active region structure. Invarious embodiments, the transistors M9-M10 in the integrated circuit 50include separated active region structure, and the transistors M0-M1 andM5-M6 include shared active region structure.

Reference is now made to FIG. 11 . FIG. 11 is a flow chart of a method1100 of operating the integrated circuit 10, 20, 40 or 50, in accordancewith some embodiments. It is understood that additional operations canbe provided before, during, and after the processes shown by FIG. 11 ,and some of the operations described below can be replaced oreliminated, for additional embodiments of the method. The order of theoperations/processes may be interchangeable. Throughout the variousviews and illustrative embodiments, like reference numbers are used todesignate like elements. The method 1100 includes operations 1110-1130that are described below with reference to the integrated circuit 10 inFIG. 2 .

In operation 1110, as shown in FIG. 2 , the transistor M2 generates theinitiation voltage to turn on the transistor M0, in which the gate andthe drain of transistor M2 are coupled to the gate of the transistor M0at the node N1. As mentioned above, in some embodiments, the initiationvoltage equals the threshold voltage of the transistor M2.

In operation 1120, as shown in FIG. 2 , the transistor M0 adjusts thevoltage level of the node N2 according to the supply voltage VDD. Thetransistor M0 is coupled to the transistor M1 at the node N2.

In some embodiments, adjusting the voltage level of the node N2 includestransmitting by the transistor M0 the supply voltage VDD to the node N2to turn on the transistor M1.

In operation 1130, as shown in FIG. 2 , the turned-on transistor M1adjusts the voltage level of the node N1 according the supply voltageVSS different from the supply voltage VDD.

In some embodiments, adjusting the voltage level of the node N1 includestransmitting by the transistor M1 the supply voltage VSS to the node N1,and therefore, the voltage level of the node N1 is pulled down from thethreshold voltage of the transistor M2 to the supply voltage VSS. Insome embodiments, the supply voltage VSS is a ground voltage.

In some embodiments, the method 1100 further includes turning on, inresponse to the initiation voltage, the transistor M3, and therefore,the transistor M3 operates as the de-coupling capacitive unit 200. Thetransistor M3 is coupled to the node N1.

In some embodiments, the method 1100 further includes directing the ESDcurrent from the transistor M3, through the transistor M2 (i.e., throughthe electrostatic discharge path P1), to the supply voltage terminal VSSproviding the supply voltage VSS.

Similarly, as the embodiments in FIG. 7 , in operation 1110, thetransistor M9 generates the initiation voltage to turn on the transistorM1, in which the gate and the drain of transistor M9 are coupled to thegate of the transistor M1 at the node N2. As mentioned above, in someembodiments, the initiation voltage equals the supply voltage VDDsubtracted by the threshold voltage of the transistor M9.

In operation 1120, as shown in FIG. 7 , the transistor M1 adjusts thevoltage level of the node N1 according to the supply voltage VSS. Thetransistor M1 is coupled to the transistor M0 at the node N1.

In some embodiments, adjusting the voltage level of the node N1 includestransmitting by the transistor M1 the supply voltage VSS to the node N1to turn on the transistor M0.

In operation 1130, as shown in FIG. 7 , the turned-on transistor M0adjusts the voltage level of the node N2 according the supply voltageVDD different from the supply voltage VSS.

In some embodiments, adjusting the voltage level of the node N2 includestransmitting by the transistor M0 the supply voltage VDD to the node N2,and therefore, the voltage level of the node N2 is pulled up to thesupply voltage VDD.

In some embodiments, the method 1100 further includes turning on, inresponse to the initiation voltage, the transistor M4, and therefore,the transistor M4 operates as the de-coupling capacitive unit 300. Thetransistor M4 is coupled to the node N2.

In some embodiments, the method 1100 further includes directing the ESDcurrent from the transistor M4, through the transistor M9 (i.e., throughthe electrostatic discharge path P4), to the supply voltage terminal VDDproviding the supply voltage VDD.

Reference is now made to FIG. 12 . FIG. 12 is a block diagram of anelectronic design automation (EDA) system 1200 for designing theintegrated circuit layout design, in accordance with some embodiments ofthe present disclosure. EDA system 1200 is configured to implement oneor more operations of the method 1100 disclosed in FIG. 11 , and furtherexplained in conjunction with FIGS. 1A-10B. In some embodiments, EDAsystem 1200 includes an APR system.

In some embodiments, EDA system 1200 is a general purpose computingdevice including a hardware processor 1202 and a non-transitory,computer-readable storage medium 1204. Storage medium 1204, amongstother things, is encoded with, i.e., stores, computer program code(instructions) 1206, i.e., a set of executable instructions. Executionof instructions 1206 by hardware processor 1202 represents (at least inpart) an EDA tool which implements a portion or all of, e.g., the method1100.

The processor 1202 is electrically coupled to computer-readable storagemedium 1204 via a bus 1208. The processor 1202 is also electricallycoupled to an I/O interface 1210 and a fabrication tool 1216 by bus1208. A network interface 1212 is also electrically connected toprocessor 1202 via bus 1208. Network interface 1212 is connected to anetwork 1214, so that processor 1202 and computer-readable storagemedium 1204 are capable of connecting to external elements via network1214. The processor 1202 is configured to execute computer program code1206 encoded in computer-readable storage medium 1204 in order to causeEDA system 1200 to be usable for performing a portion or all of thenoted processes and/or methods. In one or more embodiments, processor1202 is a central processing unit (CPU), a multi-processor, adistributed processing system, an application specific integratedcircuit (ASIC), and/or a suitable processing unit.

In one or more embodiments, computer-readable storage medium 1204 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example,computer-readable storage medium 1204 includes a semiconductor orsolid-state memory, a magnetic tape, a removable computer diskette, arandom access memory (RAM), a read-only memory (ROM), a rigid magneticdisk, and/or an optical disk. In one or more embodiments using opticaldisks, computer-readable storage medium 1204 includes a compactdisk-read only memory (CD-ROM), a compact disk-read/write (CD-R/W),and/or a digital video disc (DVD).

In one or more embodiments, storage medium 1204 stores computer programcode 1206 configured to cause EDA system 1200 (where such executionrepresents (at least in part) the EDA tool) to be usable for performinga portion or all of the noted processes and/or methods. In one or moreembodiments, storage medium 1204 also stores information whichfacilitates performing a portion or all of the noted processes and/ormethods. In one or more embodiments, storage medium 1204 stores IClayout diagram 1220 of standard cells including such standard cells asdisclosed herein, for example, a cell including in the integratedcircuits 10, 20, 40 and/or 50 discussed above with respect to FIGS.1A-10B.

EDA system 1200 includes I/O interface 1210. I/O interface 1210 iscoupled to external circuitry. In one or more embodiments, I/O interface1210 includes a keyboard, keypad, mouse, trackball, trackpad,touchscreen, and/or cursor direction keys for communicating informationand commands to processor 1202.

EDA system 1200 also includes network interface 1212 coupled toprocessor 1202. Network interface 1212 allows EDA system 1200 tocommunicate with network 1214, to which one or more other computersystems are connected. Network interface 1212 includes wireless networkinterfaces such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wirednetwork interfaces such as ETHERNET, USB, or IEEE-1264. In one or moreembodiments, a portion or all of noted processes and/or methods, isimplemented in two or more systems 1200.

EDA system 1200 also includes the fabrication tool 1216 coupled toprocessor 1202. The fabrication tool 1216 is configured to fabricateintegrated circuits, e.g., the integrated circuits 10, 20, and 40-50illustrated in FIGS. 1A-10B, according to the design files processed bythe processor 1202.

EDA system 1200 is configured to receive information through I/Ointerface 1210. The information received through I/O interface 1210includes one or more of instructions, data, design rules, libraries ofstandard cells, and/or other parameters for processing by processor1202. The information is transferred to processor 1202 via bus 1208. EDAsystem 1200 is configured to receive information related to a UI throughI/O interface 1210. The information is stored in computer-readablemedium 1204 as design specification 1222.

In some embodiments, a portion or all of the noted processes and/ormethods is implemented as a standalone software application forexecution by a processor. In some embodiments, a portion or all of thenoted processes and/or methods is implemented as a software applicationthat is a part of an additional software application. In someembodiments, a portion or all of the noted processes and/or methods isimplemented as a plug-in to a software application. In some embodiments,at least one of the noted processes and/or methods is implemented as asoftware application that is a portion of an EDA tool. In someembodiments, a portion or all of the noted processes and/or methods isimplemented as a software application that is used by EDA system 1200.In some embodiments, a layout diagram which includes standard cells isgenerated using a tool such as VIRTUOSO® available from CADENCE DESIGNSYSTEMS, Inc., or another suitable layout generating tool.

In some embodiments, the processes are realized as functions of aprogram stored in a non-transitory computer readable recording medium.Examples of a non-transitory computer readable recording medium include,but are not limited to, external/removable and/or internal/built-instorage or memory unit, for example, one or more of an optical disk,such as a DVD, a magnetic disk, such as a hard disk, a semiconductormemory, such as a ROM, a RAM, a memory card, and the like.

FIG. 13 is a block diagram of IC manufacturing system 1300, and an ICmanufacturing flow associated therewith, in accordance with someembodiments. In some embodiments, based on a layout diagram, at leastone of (A) one or more semiconductor masks or (B) at least one componentin a layer of a semiconductor integrated circuit is fabricated using ICmanufacturing system 1300.

In FIG. 13 , IC manufacturing system 1300 includes entities, such as adesign house 1320, a mask house 1330, and an IC manufacturer/fabricator(“fab”) 1350, that interact with one another in the design, development,and manufacturing cycles and/or services related to manufacturing an ICdevice 1360. The entities in IC manufacturing system 1300 are connectedby a communications network. In some embodiments, the communicationsnetwork is a single network. In some embodiments, the communicationsnetwork is a variety of different networks, such as an intranet and theInternet. The communications network includes wired and/or wirelesscommunication channels. Each entity interacts with one or more of theother entities and provides services to and/or receives services fromone or more of the other entities. In some embodiments, two or more ofdesign house 1320, mask house 1330, and IC fab 1350 is owned by a singlelarger company. In some embodiments, two or more of design house 1320,mask house 1330, and IC fab 1350 coexist in a common facility and usecommon resources.

Design house (or design team) 1320 generates an IC design layout diagram1322. IC design layout diagram 1322 includes various geometricalpatterns, for example, an IC layout design depicted in FIGS. 3, 5A-5B,8, and 10A-10B, designed for an IC device 1360, for example, integratedcircuits 10, 20, 40, and 50 discussed above with respect to FIGS.1A-10B. The geometrical patterns correspond to patterns of metal, oxide,or semiconductor layers that make up the various components of IC device1360 to be fabricated. The various layers combine to form various ICfeatures. For example, a portion of IC design layout diagram 1322includes various IC features, such as an active region, gate electrode,source and drain, conductive segments or vias of an interlayerinterconnection, to be formed in a semiconductor substrate (such as asilicon wafer) and various material layers disposed on the semiconductorsubstrate. Design house 1320 implements a proper design procedure toform IC design layout diagram 1322. The design procedure includes one ormore of logic design, physical design or place and route. IC designlayout diagram 1322 is presented in one or more data files havinginformation of the geometrical patterns. For example, IC design layoutdiagram 1322 can be expressed in a GDSII file format or DFII fileformat.

Mask house 1330 includes data preparation 1332 and mask fabrication1344. Mask house 1330 uses IC design layout diagram 1322 to manufactureone or more masks 1345 to be used for fabricating the various layers ofIC device 1360 according to IC design layout diagram 1322. Mask house1330 performs mask data preparation 1332, where IC design layout diagram1322 is translated into a representative data file (“RDF”). Mask datapreparation 1332 provides the RDF to mask fabrication 1344. Maskfabrication 1344 includes a mask writer. A mask writer converts the RDFto an image on a substrate, such as a mask (reticle) 1345 or asemiconductor wafer 1353. The IC design layout diagram 1322 ismanipulated by mask data preparation 1332 to comply with particularcharacteristics of the mask writer and/or requirements of IC fab 1350.In FIG. 13 , data preparation 1332 and mask fabrication 1344 areillustrated as separate elements. In some embodiments, data preparation1332 and mask fabrication 1344 can be collectively referred to as maskdata preparation.

In some embodiments, data preparation 1332 includes optical proximitycorrection (OPC) which uses lithography enhancement techniques tocompensate for image errors, such as those that can arise fromdiffraction, interference, other process effects and the like. OPCadjusts IC design layout diagram 1322. In some embodiments, datapreparation 1332 includes further resolution enhancement techniques(RET), such as off-axis illumination, sub-resolution assist features,phase-shifting masks, other suitable techniques, and the like orcombinations thereof. In some embodiments, inverse lithographytechnology (ILT) is also used, which treats OPC as an inverse imagingproblem.

In some embodiments, data preparation 1332 includes a mask rule checker(MRC) that checks the IC design layout diagram 1322 that has undergoneprocesses in OPC with a set of mask creation rules which contain certaingeometric and/or connectivity restrictions to ensure sufficient margins,to account for variability in semiconductor manufacturing processes, andthe like. In some embodiments, the MRC modifies the IC design layoutdiagram 1322 to compensate for limitations during mask fabrication 1344,which may undo part of the modifications performed by OPC in order tomeet mask creation rules.

In some embodiments, data preparation 1332 includes lithography processchecking (LPC) that simulates processing that will be implemented by ICfab 1350 to fabricate IC device 1360. LPC simulates this processingbased on IC design layout diagram 1322 to create a simulatedmanufactured device, such as IC device 1360. The processing parametersin LPC simulation can include parameters associated with variousprocesses of the IC manufacturing cycle, parameters associated withtools used for manufacturing the IC, and/or other aspects of themanufacturing process. LPC takes into account various factors, such asaerial image contrast, depth of focus (“DOF”), mask error enhancementfactor (“MEEF”), other suitable factors, and the like or combinationsthereof. In some embodiments, after a simulated manufactured device hasbeen created by LPC, if the simulated device is not close enough inshape to satisfy design rules, OPC and/or MRC are be repeated to furtherrefine IC design layout diagram 1322.

It should be understood that the above description of data preparation1332 has been simplified for the purposes of clarity. In someembodiments, data preparation 1332 includes additional features such asa logic operation (LOP) to modify the IC design layout diagram 1322according to manufacturing rules. Additionally, the processes applied toIC design layout diagram 1322 during data preparation 1332 may beexecuted in a variety of different orders.

After data preparation 1332 and during mask fabrication 1344, a mask1345 or a group of masks 1345 are fabricated based on the modified ICdesign layout diagram 1322. In some embodiments, mask fabrication 1344includes performing one or more lithographic exposures based on ICdesign layout diagram 1322. In some embodiments, an electron-beam(e-beam) or a mechanism of multiple e-beams is used to form a pattern ona mask (photomask or reticle) 1345 based on the modified IC designlayout diagram 1322. Mask 1345 can be formed in various technologies. Insome embodiments, mask 1345 is formed using binary technology. In someembodiments, a mask pattern includes opaque regions and transparentregions. A radiation beam, such as an ultraviolet (UV) beam, used toexpose the image sensitive material layer (for example, photoresist)which has been coated on a wafer, is blocked by the opaque region andtransmits through the transparent regions. In one example, a binary maskversion of mask 1345 includes a transparent substrate (for example,fused quartz) and an opaque material (for example, chromium) coated inthe opaque regions of the binary mask. In another example, mask 1345 isformed using a phase shift technology. In a phase shift mask (PSM)version of mask 1345, various features in the pattern formed on thephase shift mask are configured to have proper phase difference toenhance the resolution and imaging quality. In various examples, thephase shift mask can be attenuated PSM or alternating PSM. The mask(s)generated by mask fabrication 1344 is used in a variety of processes.For example, such a mask(s) is used in an ion implantation process toform various doped regions in semiconductor wafer 1353, in an etchingprocess to form various etching regions in semiconductor wafer 1353,and/or in other suitable processes.

IC fab 1350 includes wafer fabrication 1352. IC fab 1350 is an ICfabrication business that includes one or more manufacturing facilitiesfor the fabrication of a variety of different IC products. In someembodiments, IC Fab 1350 is a semiconductor foundry. For example, theremay be a manufacturing facility for the front end fabrication of aplurality of IC products (front-end-of-line (FEOL) fabrication), while asecond manufacturing facility may provide the back end fabrication forthe interconnection and packaging of the IC products (back-end-of-line(BEOL) fabrication), and a third manufacturing facility may provideother services for the foundry business.

IC fab 1350 uses mask(s) 1345 fabricated by mask house 1330 to fabricateIC device 1360. Thus, IC fab 1350 at least indirectly uses IC designlayout diagram 1322 to fabricate IC device 1360. In some embodiments,semiconductor wafer 1353 is fabricated by IC fab 1350 using mask(s) 1345to form IC device 1360. In some embodiments, the IC fabrication includesperforming one or more lithographic exposures based at least indirectlyon IC design layout diagram 1322. Semiconductor wafer 1353 includes asilicon substrate or other proper substrate having material layersformed thereon. Semiconductor wafer 1353 further includes one or more ofvarious doped regions, dielectric features, multilevel interconnects,and the like (formed at subsequent manufacturing steps).

As described above, the integrated circuit of the present disclosureincludes a start-up circuit arranged between the two terminals ofelectrostatic discharge path to increase the ability of the integratedcircuit for electrostatic charge dissipation. In addition, theintegrated circuit also includes a control circuit that provides theinitiation voltage to the start-up circuit, so that the pull-downcircuit or the pull-up circuit included in the start-up circuit can actquickly in response to the initiation voltage; thereby the operationspeed of the start-up circuit is improved. Furthermore, with theconfiguration of the present disclosure, P-type and N-type transistorsutilized as capacitor units in the integrated circuit provide highdecoupling capacitance values with a small area.

In some embodiments, an integrated circuit includes a control circuit, afirst voltage generation circuit, and a second voltage generationcircuit. The control circuit is coupled between a first voltage terminaland a first node, and generates an initiation voltage at the first node.The first voltage generation circuit and the second voltage generationcircuit are coupled to a first capacitive unit at the first node andcoupled to a second capacitive unit at a second node. The first voltagegeneration circuit generates, in response to the initiation voltage atthe first node, a first control signal based on a first supply voltagefrom a second voltage terminal to the second voltage generation circuit.The second voltage generation circuit generates, in response to thefirst control signal received from the first voltage generation circuit,a second control signal to the first node, based on a second supplyvoltage, different from the first supply voltage, from the first voltageterminal. In some embodiments, the control circuit includes a transistorhaving a source coupled to the second voltage terminal and a drain and agate that are coupled to the first node. In some embodiments, theinitiation voltage generated by the control circuit is associated with athreshold voltage of the transistor and the first supply voltage. Insome embodiments, the first capacitive unit is coupled between the firstnode and the second voltage terminal, and the control circuit and thefirst capacitive unit are configured as an electrostatic discharge pathbetween the first voltage terminal and the second voltage terminal. Insome embodiments, the first control signal is associated with a voltagelevel of the second node, and the second control signal is associatedwith a voltage level of the first node. In some embodiments, the firstvoltage generation circuit includes a P-type transistor having a gatecoupled to the first node and a drain coupled to the second node. Thesecond voltage generation circuit includes a N-type transistor having agate coupled to the second node and a drain coupled to the first node.In some embodiments, the first voltage generation circuit includesmultiple first transistors coupled in series with each other and thesecond voltage generation circuit includes multiple second transistorscoupled in series with each other. The control circuit includes multiplethird transistors coupled in series with each other. A number of thefirst transistors is different than a sum of a number of the secondtransistors and a number of the third transistors. In some embodiments,the first transistors are P-type, and the second transistors and thethird transistors are N-type. The number of the first transistors issmaller than the sum of the number of the second transistors and thenumber of the third transistors. In some embodiments, the controlcircuit includes a transistor having a source coupled to the firstvoltage terminal and a drain and a gate that are coupled to the firstnode. When the first voltage terminal is a ground terminal, theinitiation voltage equals to a threshold voltage of the transistor. Thesecond voltage generation circuit pulls down a voltage of the first nodeto a ground voltage of the ground terminal. In some embodiments, thesecond voltage generation circuit includes a transistor having a firstterminal coupled to the first node, a second terminal coupled to thefirst voltage terminal, and a control terminal coupled to the secondnode. The second voltage generation circuit and the first capacitiveunit are as an electrostatic discharge path to direct an electrostaticdischarge current from the first voltage terminal, through the firstcapacitive unit, and the first terminal and the second terminal of thetransistor, to the second voltage terminal.

Also disclosed is an integrated circuit that includes a first conductiveline and a second conductive line that extend in a first direction, afirst gate, a second gate and a third active region, and a third gate.The first gate is coupled to the first conductive line and arrangedbetween a first active region and a second active region that arecoupled to a first voltage terminal. The second gate and the thirdactive region are coupled to the first conductive line. The second gateis arranged between the third active region and a fourth active regioncoupled to a second voltage terminal. The third gate is separated fromthe second gate in the first direction, coupled to the second conductiveline, and arranged between the third active region and a fifth activeregion coupled to the second voltage terminal. The first gate, the firstactive region and second active region are included in a structureoperating as a first transistor. The second gate, the third activeregion and fourth active region are included in a structure operating asa second transistor. The third gate, the third active region and fifthfourth active region are included in a structure operating as a thirdtransistor. The first to third transistors and the first conductive linedischarge a first portion of an electrostatic discharge current betweenthe first voltage terminal and the second voltage terminal. In someembodiments, the first conductive line and the second conductive lineare arranged between the first active region and the fifth activeregion. In some embodiments, the integrated circuit further includes afourth gate and a fifth gate. The fourth gate is coupled to the firstconductive line and arranged between the first active region and a sixthactive region coupled to the second conductive line. The fourth gate,the fifth active region, and the sixth active region are included in astructure operating as a fourth transistor. The fifth gate is coupled tothe second conductive line and arranged between the fifth active regionand a seventh active region coupled to the second voltage terminal. Whenthe fourth transistor is turned on in response to a voltage generated bythe second transistor to the first conductive line, the fourthtransistor, the second conductive line, the fifth gate, and the fifthand seventh active regions are configured to discharge a second portionof the electrostatic discharge current between the first voltageterminal or the second voltage terminal. In some embodiments, theintegrated circuit further includes a fourth gate which is separatedfrom the second gate in the first direction and coupled to the firstconductive line. The fourth gate is included in a structure operating asa fourth transistor. The second transistor and the fourth transistor arecoupled in series between the first conductive line and the secondvoltage terminal. In some embodiments, the integrated circuit furtherincludes a sixth active region and a seventh active region coupled tothe sixth active region. The sixth active region is included in astructure corresponding to a source of the second transistor, and theseventh active region is included in a structure corresponding to adrain of the fourth transistor. The sixth active region and the seventhactive region are separated with each other in the first direction.

Also disclosed is a method that includes the operation below: generatingan initiation voltage, by at least one first transistor, to turn on atleast one second transistor, in which a gate and a first terminal of theat least one first transistor are coupled to a gate of the at least onesecond transistor at a first node; adjusting, by the at least one secondtransistor, a voltage level of a second node according to a first supplyvoltage, in which the at least one second transistor is coupled to atleast one third transistor at the second node; and adjusting, by the atleast one third transistor, a voltage level of the first node accordingto a second supply voltage different from the first supply voltage. Insome embodiments, adjusting the voltage level of the second nodeincludes transmitting, by the at least one second transistor, the firstsupply voltage to the second node to turn on the at least one thirdtransistor. In some embodiments, adjusting the voltage level of thefirst node includes pulling down the voltage level of the first nodefrom a threshold voltage of the at least one first transistor to thesecond supply voltage. In some embodiments, the method further includesturning on, in response to the initiation voltage, a fourth transistoroperating as a decoupling capacitive unit, wherein a gate of the fourthtransistor is coupled to the first node. In some embodiments, the methodfurther includes directing an electrostatic discharge current flowingfrom the fourth transistor, through the at least one first transistor,to a voltage terminal providing the second supply voltage.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated circuit, comprising: a controlcircuit coupled between a first voltage terminal and a first node, andconfigured to generate an initiation voltage at the first node; and afirst voltage generation circuit and a second voltage generation circuitthat are coupled to a first capacitive unit at the first node andcoupled to a second capacitive unit at a second node, wherein the firstvoltage generation circuit is configured to generate, in response to theinitiation voltage at the first node, a first control signal based on afirst supply voltage from a second voltage terminal to the secondvoltage generation circuit, wherein the first voltage generation circuitcomprises a plurality of first transistors coupled in series with eachother between the second node and the second voltage terminal, and thesecond voltage generation circuit is configured to generate, in responseto the first control signal received from the first voltage generationcircuit, a second control signal to the first node, based on a secondsupply voltage, different from the first supply voltage, from the firstvoltage terminal.
 2. The integrated circuit of claim 1, wherein thecontrol circuit comprises: a transistor having a source coupled to thesecond voltage terminal and a drain and a gate that are coupled to thefirst node.
 3. The integrated circuit of claim 2, wherein the initiationvoltage generated by the control circuit is associated with a thresholdvoltage of the transistor and the first supply voltage.
 4. Theintegrated circuit of claim 1, wherein the first capacitive unit iscoupled between the first node and the second voltage terminal, and thecontrol circuit and the first capacitive unit are configured as anelectrostatic discharge path between the first voltage terminal and thesecond voltage terminal.
 5. The integrated circuit of claim 1, whereinthe first control signal is associated with a voltage level of thesecond node, and the second control signal is associated with a voltagelevel of the first node.
 6. The integrated circuit of claim 1, whereinthe second voltage generation circuit comprises a N-type transistorhaving a gate coupled to the second node and a drain coupled to thefirst node.
 7. The integrated circuit of claim 1, wherein the secondvoltage generation circuit comprises a plurality of second transistorscoupled in series with each other, wherein the control circuit comprisesa plurality of third transistors coupled in series with each other;wherein a number of the plurality of first transistors is different thana sum of a number of the plurality of second transistors and a number ofthe plurality of third transistors.
 8. The integrated circuit of claim7, wherein the plurality of first transistors are P-type, and theplurality of second transistors and the plurality of third transistorsare N-type; wherein the number of the plurality of first transistors issmaller than the sum of the number of the plurality of secondtransistors and the number of the plurality of third transistors.
 9. Theintegrated circuit of claim 1, wherein the control circuit comprises: atransistor having a source coupled to the first voltage terminal and adrain and a gate that are coupled to the first node, wherein when thefirst voltage terminal is a ground terminal, the initiation voltageequals to a threshold voltage of the transistor; wherein the secondvoltage generation circuit is configured to pull down a voltage of thefirst node to a ground voltage of the ground terminal.
 10. Theintegrated circuit of claim 1, wherein the second voltage generationcircuit comprises: a transistor having a first terminal coupled to thefirst node, a second terminal coupled to the first voltage terminal, anda control terminal coupled to the second node; wherein the secondvoltage generation circuit and the first capacitive unit are configuredas an electrostatic discharge path to direct an electrostatic dischargecurrent from the first voltage terminal, through the first capacitiveunit, and the first terminal and the second terminal of the transistor,to the second voltage terminal.
 11. An integrated circuit, comprising: afirst conductive line and a second conductive line that extend in afirst direction; a first gate coupled to the first conductive line andarranged between a first active region and a second active region thatare coupled to a first voltage terminal; a second gate and a thirdactive region that are coupled to the first conductive line, wherein thesecond gate is arranged between the third active region and a fourthactive region coupled to a second voltage terminal; and a third gatewhich is separated from the second gate in the first direction, coupledto the second conductive line, and arranged between the third activeregion and a fifth active region coupled to the second voltage terminal;wherein the first gate, the first active region and second active regionare included in a structure operating as a first transistor, wherein thesecond gate, the third active region and fourth active region areincluded in a structure operating as a second transistor, wherein thethird gate, the third active region and fifth fourth active region areincluded in a structure operating as a third transistor; wherein thefirst to third transistors and the first conductive line are configuredto discharge a first portion of an electrostatic discharge currentbetween the first voltage terminal and the second voltage terminal. 12.The integrated circuit of claim 11, wherein the first conductive lineand the second conductive line are arranged between the first activeregion and the fifth active region.
 13. The integrated circuit of claim11, further comprising: a fourth gate coupled to the first conductiveline and arranged between the first active region and a sixth activeregion coupled to the second conductive line, wherein the fourth gate,the fifth active region, and the sixth active region are included in astructure operating as a fourth transistor; and a fifth gate coupled tothe second conductive line and arranged between the fifth active regionand a seventh active region coupled to the second voltage terminal;wherein when the fourth transistor is turned on in response to a voltagegenerated by the second transistor to the first conductive line, thefourth transistor, the second conductive line, the fifth gate, and thefifth and seventh active regions are configured to discharge a secondportion of the electrostatic discharge current between the first voltageterminal or the second voltage terminal.
 14. The integrated circuit ofclaim 11, further comprising: a fourth gate which is separated from thesecond gate in the first direction and coupled to the first conductiveline, wherein the fourth gate is included in a structure operating as afourth transistor; wherein the second transistor and the fourthtransistor are coupled in series between the first conductive line andthe second voltage terminal.
 15. The integrated circuit of claim 14,further comprising: a sixth active region and a seventh active regioncoupled to the sixth active region; wherein the sixth active region isincluded in a structure corresponding to a source of the secondtransistor, and the seventh active region is included in a structurecorresponding to a drain of the fourth transistor; wherein the sixthactive region and the seventh active region are separated with eachother in the first direction.
 16. A method, comprising: generating aninitiation voltage, by a plurality of first transistors that are coupledin series, to turn on at least one second transistor, wherein gate andfirst terminals of the plurality of first transistors are coupled to agate of the at least one second transistor at a first node; adjusting,by the at least one second transistor, a voltage level of a second nodeaccording to a first supply voltage, wherein the at least one secondtransistor is coupled to at least one third transistor at the secondnode; and adjusting, by the at least one third transistor, a voltagelevel of the first node according to a second supply voltage differentfrom the first supply voltage.
 17. The method of claim 16, whereinadjusting the voltage level of the second node comprises: transmitting,by the at least one second transistor, the first supply voltage to thesecond node to turn on the at least one third transistor.
 18. The methodof claim 16, wherein adjusting the voltage level of the first nodecomprises: pulling down the voltage level of the first node from athreshold voltage of the plurality of first transistors to the secondsupply voltage.
 19. The method of claim 16, further comprising: turningon, in response to the initiation voltage, a fourth transistor operatingas a decoupling capacitive unit, wherein a gate of the fourth transistoris coupled to the first node.
 20. The method of claim 19, furthercomprising: directing an electrostatic discharge current flowing fromthe fourth transistor, through the plurality of first transistors, to avoltage terminal providing the second supply voltage.